


Biology

by Araine



Category: Doctor Who & Related Fandoms, Doctor Who (2005)
Genre: Alternate Universe - Canon, Community: comment_fic, Donna Noble: Time Lady, Episode: s04e13 Journey's End, Fix-It, Gen, Technobabble
Language: English
Status: Completed
Published: 2011-02-18
Updated: 2011-02-18
Packaged: 2017-10-15 18:29:09
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,018
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/163645
Author URL: https://archiveofourown.org/users/Araine/pseuds/Araine
Summary: <blockquote class="userstuff">
              <p>“Human synapses can’t handle a Time Lord consciousness, too much information, too much electricity working in your brains all at once, like trying to fit too much air into a balloon, it just bursts.”</p><p>The Doctor can save Donna, but only at a cost. Donna Noble must still die.</p>
            </blockquote>





	Biology

**Author's Note:**

> Picks up in the middle of the scene at the end of Journey's End where the Doctor erases Donna's memory, but goes AU from there.

“No. Oh, my God... I can't go back. Don't make me go back. Doctor... please. Please, don't make me go back.”

The Doctor looked at her with soft eyes, seeing with them Donna Noble, Best Temp In All of Chiswick, and the Doctor-Donna, everything that she was and had been and could be in one brilliant moment. But he would not, could not, lose another life today, not after all that had been lost, even if she would rather that she burned with the fire of a mind that her biology couldn’t handle…

“Biology.”

There was something about biology. Something about cells: brain cells, nerve cells. It was on the tip of his tongue.

“Doctor?” Tears still shivered down Donna’s cheeks, but she was confused, now, not desperate.

“Your biology, your cells,” the Doctor said, stepping back from Donna now, his eyes wild. “Human synapses can’t handle a Time Lord consciousness, too much information, too much electricity working in your brains all at once, like trying to fit too much air into a balloon, it just bursts.” He was full-on rambling now, but Donna understood him, though her head was running in circles. “But, if you get a bigger balloon – or, no, one with stretchier rubber, well, that would change things.”

“Change the surface area and you exponentially increase the volume,” Donna said. “Right, but I’m not a balloon. You can’t just _change_ the surface area of my brain.”

“Well, no,” the Doctor said. “You’re not a balloon. But you _are_ human – or, mostly human – and humans are built on DNA. Most of the universe is actually, isn’t that brilliant? I love the stuff. You can go halfway across the universe and life is creating itself on the same code—“

“Doctor!” Donna was growing right impatient with him. Her head was throbbing, like she was coming on with the world’s greatest migraine, but she knew it was more than that, because she was suddenly warm and then suddenly cold and her eyes had gone all jittery and she couldn’t think of a way to save herself even in all of her new knowledge save freezing the knowledge stone cold inside of her head, and it _hurt_ and—and he was rambling!

The gravitas of the situation at hand returned to him, and the Doctor took a breath. “Right,” he said. “DNA. Tinker Toys of life, you put it together in the right combination and it can create a whole being, flesh and blood. Changing DNA, well, that’s easy enough – it can get flummoxed by a simple bit of radiation. But changing it _correctly_ , that’s the tricky part. There’s only one thing that can do that.”

Donna arrived at the conclusion as soon as he had said it, and she looked up to where a small headset hung innocuously from the ceiling.

“The Chameleon Arch,” she said, half in awe at his brilliance and half in disbelief that it could work. When she looked back to the Doctor, he was grinning in that manic way that he had. “Are you sure that it would work?”

“I’m sure I could reverse engineer it,” he said.

“But Time Lord DNA is too complicated,” Donna said, her mouth suddenly dry. “It can only be stored. Not replicated—rewritten—removed—rejected—re— _copied_.” She gasped. She could feel that headache that meant that her brain was burning up inside of her, and felt a sudden despair. “I’m human. We can’t trick my biology into being Time Lord.”

The Doctor did not seem fazed by this at all. “But that’s the brilliant thing,” he said. “The metacrisis already tricked your biology. Now we just have to take the next step.”

Donna stared at him. For the first time, she truly believed that she might be saved.

“Just simple biologic protoengineering,” Donna said. “With the Chameleon Arch to augment the transcription factors, we could rewrite my cells—bells—swells—fells—dells—“ Donna stopped herself, breathing harsh.

“It’s speeding up,” the Doctor said. “We’ll have to work fast.”

Donna nodded.

The Doctor looked at her with those sad, level eyes once more. Donna looked back into them. “It’s going to hurt,” he said. “A lot. You might die.”

“I know.”

“You won’t be you, anymore.”

“I don’t care.”  
The Doctor spent another moment looking at her, and then turned to the console of the TARDIS. “Right, then,” he said. “Better get started.”

The Chameleon Arch was already set to human, which was a boon, as it saved a certain amount of time. The Doctor pulled his Sonic from his jacket pocket. It was a cheat, and it would probably be better to actually fiddle with the wires _instead_ of just reversing their magnetism, but time was of the essence and he had never liked fiddling with wires all that much anyways.

It only took the space of a few minutes.

“All done,” the Doctor said, but his brows were knitted together in concentration. “But—it’s missing something.”

Donna grimaced. “A forgeable biological signature,” she said.

“Exactly,” the Doctor said. He was frowning at the headset in front of him. “Normally it wouldn’t be a problem, it would just pick up traces from the air. But Time Lord biology is so complex, it takes a _huge_ amount of energy just to change our own. Donna, I’m sorry.”

“Yeah,” she said. “Me too.”

“Donna Noble,” he said, shaking his head, all of his admiration and sorrow for this woman filling him. “We had the best of times.”

The Doctor stepped forward, reaching out to bring his hands to her face, to save her in the only way that he could—

“Wait, no.” Donna said. “Doctor.” He continued moving toward her. “Doctor!” Donna stepped back and raised her voice. “Oi! Not another step, spaceman! I’m _thinking_!”

The Doctor stopped in his tracks, eyes wide and blinking.

“ _We_ need a blast of energy that can rewrite DNA in order to create a useable biological signature for the Chameleon Arch,” Donna said. “Time Lord regeneration energy would do the trick, only you can’t find that unless you’ve got a Time Lord who’s regenerating. Which you _are_ , in case you forgot that bit, starfish-boy.”

The Doctor looked at her, mouth wide in astonishment. And then he grinned. “Donna, that’s brilliant!”

Donna smiled back at him. “I know,” she said. “You shunted off a lot of your Time Lord energy into that hand of yours, but not all of it, and not all of that went to healing yourself. You’re still in the first fourteen hours of your regeneration cycle, and _all_ of that energy is still bouncing around inside you.”

“And _that_ means that if I circuit the wires to connect to me, the Chameleon Arch will be able to use the regeneration energy as an original to copy from.”

Donna shuddered and gasped. Her brain felt like it was going to burst out of her skull—she pressed her hands to her temples, and found that she was feverish, but she couldn’t feel it—

“Come on, Donna! No time to waste!”

She nodded, not trusting herself to speak.

He settled the Chameleon Arch over her head, pulled out a wire from atop it, and quickly soniced it into the configuration that he wanted. He turned the Chameleon Arch on.

“Allons-y!”

Regeneration energy flowed from him in a stream of golden energized particles and into the machine. Donna began to scream with the sudden pain of it—

Her skin began to glow. Slowly at first, just a faint shimmer through her eyelids, and then spreading and shifting, the energy changing her just as much as the Arch—

The light burst from her, filling the inside of the TARDIS with an effervescent glow that hummed and resonated with the ancient machine-that-is-not-a-machine. As she glowed and changed, the Doctor saw Donna Noble, everything that she was and everything that she had been and everything that she could be, everything that she _would_ now become—

Suddenly, he was not so very alone as he thought. They weren’t just tricking her biology, as the Chameleon Arch might – but with that bit of Time Lord regeneration energy funneled into her, they had truly _rewritten_ it…

He smiled. The Doctor-Donna. The entire universe had been waiting.

After a few moments, it was done.

“Donna, you’re a Time Lord now.”

“Oi! I _am_ a girl. Time _Lady_ , thank you.”

Some things even biology couldn’t change.

\--

“Donna! That must be Donna!”

The Doctor heard the voice of Wilfred Mott from inside, and a moment later he wrenched open the door to find the Time Lord standing there with Donna at his side. Wrinkles that he probably hadn’t even noticed eased from his brow at the sight of them.

“Sylvia! Donna’s back!” He called into the house.

“Hey, Gramps,” Donna said softly. She smiled, but it didn’t show her teeth, and the edges of her eyes crinkled only a little.

Wilfred reached out to hug her tightly. “You saved the world, sweetheart!” he said. “Planets in the sky, aliens all over, me with my paintball gun – and who saved us all? My Donna Noble. Not too shabby, eh?” he said.

Donna shook her head with a wry smile. “No,” she said. “Not all that shabby, I suppose.”

“And here I was, thinking something bad had happened,” Wilfred said. He laughed. “Come on in for some tea. You too, Doctor, would you like some tea?”

“Oh, I’d love tea,” the Doctor said. “Coming, Donna?”

“Yeah,” she said. The Doctor peered at her inquisitively, but Donna followed her grandfather inside to say hello to her mother, so he said nothing.

They both greeted Sylvia Noble, but once they had their tea Donna pleaded tiredness and shooed her family out of the room. The Doctor let them go.

“You’re not tired,” he said once the two of them had disappeared around the corner. “It takes a lot more than what happened today to tire out a Time Lord – especially a new one. What’s wrong?”

Donna shook her head. “It’s just—how long do Time Lords live?” she asked.

The Doctor thought about that. “Oh, if you’re careful with your regenerations—a long time. A _really_ long time. I’m nine hundred, and I’m not very careful. Have been for awhile, actually.”

“How can you be nine hundred for a while?” Donna said.

“Oh, uh,” the Doctor said. “A thousand sounds a bit old, don’t you think? It’s like when you’re thirty-nine for a couple of years.”

“Right,” Donna said. She had never really thought of the Doctor as being vain about his age, but she supposed it could happen to anybody. “It’s… when I saw my family, I saw how _fragile_ they are, how quickly they’ll… well, you know.”

The Doctor nodded slowly, and his eyes met hers from across the table. Old and terribly sad eyes that Donna had never quite understood before now. “It hurts,” he said. “I know. And I’m not going to say it gets better because it doesn’t.”

“No, I suppose it wouldn’t,” Donna said. “But then, that’d be kind of horrible if it did.”

The Doctor smiled at her with half of his mouth.

“Everything’s changed now, hasn’t it?”

“It’s like Dalek Caan said. ‘One will still die’. That was Donna Noble. The _human_ Donna Noble. You can’t ever go back to that – even if you could do it safely, we permanently changed your biology.” The Doctor had never been one to mince his words. It was strange to think of Donna Noble as dead when she carried around all of Donna Noble’s identity and memories, but there it was.

Donna Noble – the Donna Noble she had been – was irretrievably gone.

“Doesn’t mean you can’t make the best of it,” the Doctor said.

“Yeah, I suppose you’re right,” Donna said. She smiled at him.

The Doctor smiled back.

“Felspoon, once we’re done with tea? Or Charlie Chaplin?”

“I was thinking Elizabeth I, actually. I’ve always wondered what made her so cross with me.”

“Nah. How about Arthur Conan Doyle? I met Agatha Christie already, why not meet them all?”


End file.
